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Old 01-29-2010, 05:06 PM   #1
 
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50 amp sub


Hey fellas...

I have a garage with a subpanel that is fed by a tandem 50 amp circuit. I am interested in adding another sub panel to power a work shop on my property. My breaker box (200 amp service) is full, and I am wondering if I can split the power from the tandem 50 amp fuses in my main box to power both sub boxes. I dont see myself drawing power from both locations at the same time since I can only be in one place at a time. Is there a junction box to be used in such an application?
any advice would be appreciated. thanks.
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Old 01-30-2010, 10:34 AM   #2
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Not an electrician so all I can really do is give you a bump up. I do know you cannot put two conductors under one breaker connector unless it is specifically designed for that. May be that's not what your talking about.
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Old 01-30-2010, 10:41 AM   #3
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Attached or detached garage & workshop ?

I would put a 100a sub next to the 200a panel - I did this in my house
Move 120v circuits to the new 100a sub
Then add a new 240v breaker in the 200a panel for the new sub



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Old 01-30-2010, 11:13 AM   #4
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Agreed - install a sub next to the existing 200a to make some room. The 200a is full, so take the opprotunity to improve that for any future need.
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Old 01-30-2010, 11:21 AM   #5
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Why not use the existing 50 amp sub panel to feed the new sub panel. You can add another 100 amp sub to the 50 amp one you have. Unfortunately you will only have 50 amps maximum current available for the third (new) sub panel. Like Dave asked, is this attached or unattached?
There are several ways this can be accomplished.
Another suggestion is to free up some space in the main panel and run the sub panel feeder from there. (see above)
Extending the service for an unattached structure is another option.
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Old 01-30-2010, 12:49 PM   #6
 
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Wow! Thanks for all the great feed back!!
My garage is detached....about 50 yards from my house. My workshop is attached to the side of my house.
After thinking it over I think I have decided to scrap the idea of adding another sub, and just piggybacking a few 20 amp sources that are currently powering outlets in my house. I have a dedicated 20 amp powering a fridge, and a dedicated 20 amp powering my dishwasher and garbage disposal. I plan to splice these lines into my workshop.

So here is my new question.......
Can I splice the 12 guage wire that runs to the appliances like a Y and keep the Y splice inside of a junction box, or do I have to run everything in line?
Sorry for the novice questions. My electrical knowledge stems from a 1-2-3 wiring book from home depot, and some automobile wiring.

Im thinking I can run from power source, create a Y inside of a junction box that will feed the outlet in the house, and the outlet in the workshop.
My fridge pulls 6.5 amps on heavy load....so I figure as long as I do not use an appliance that pulls over 10 amps I should be safe from overloading.

As far as the dishwasher and garbage disposal line....I can not find how many amps those appliances pull,,but I hardly use the disposal, and I cant imagine the dishwasher pulling too many amps. Ill just make sure that I have the work shop shut down while using the dish washer.

I may consider adding another sub right next to the main in the future just to clean everything up....but for now I am trying to get my shop running without breaking the bank.

Any thoughts, advice, criticism, would be valued.
thanks for your time.
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Old 01-30-2010, 01:01 PM   #7
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You can't piggyback off the dishawasher & garbage disposal, against code
This required by code to be dedicated, a DW can pull 12a
Also not off the kitchen circuits, also required to be dedicated
Adding onto the fridge circuit is an extremely bad idea

Do it right the 1st time



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Old 01-30-2010, 01:29 PM   #8
 
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Quote:
Originally Posted by Scuba_Dave View Post
You can't piggyback off the dishawasher & garbage disposal, against code
This required by code to be dedicated, a DW can pull 12a
Also not off the kitchen circuits, also required to be dedicated
Adding onto the fridge circuit is an extremely bad idea

Do it right the 1st time
Ok, you have steered me away from my cheapo plan.

Can I buy an 8 slot 125a sub box, and move just 8 of the the 15a circuits over and re use the space in the main for new stuff? would I need a 125a box for that or could I use a 100amp?
How would you do it the right way? I am hoping to start this project today, but want to do it right, keep it safe, and still stay in a budget. I like this idea cause it will free up some space in the main if I ever decided to add more stuff.
My main circuit breaker says 100a, but the meter says 200 on it. do I have 200 amp service?
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Old 01-30-2010, 01:41 PM   #9
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You would only need a 100 panel
I haven't checked pricesd in a few years but a 100a main breaker panel used to go for about $60
Check & see what prices are
You really only need to move (4) circuits to the new 100 panel
That will allow room to put in a 100a 240v breaker to feed the 100a sub
And a 50a 240v breaker to feed a sub in the workshop

OR, just move 2 circuits & run single circuits as needed to the workshop
Myself I'd prefer a sub in the workshop if it's any distance

I'm not sure on the meter issue
If the main breaker on your panel states 100a then that is all you have in that panel
Is the garage fed from this panel ?
Any pic of the meter setup, any breakers out there ?



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Old 01-30-2010, 01:44 PM   #10
 
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Quote:
Originally Posted by Scuba_Dave View Post
Attached or detached garage & workshop ?

I would put a 100a sub next to the 200a panel - I did this in my house
Move 120v circuits to the new 100a sub
Then add a new 240v breaker in the 200a panel for the new sub

Ok, so from the main panel move 8 15a circuits to a 100a sub, feed the sub via w50a circuit just like my other sub??? then I can add 3 20a circuits to the main panel for the workshop and be left with 3 extra slots on my main? Is that the right way?
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Old 01-30-2010, 01:48 PM   #11
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Well the problem now is a 100a sub off a 100 main is not a good idea & may not meet code
There is a Max amount you can draw off a breaker bus via another 240v breaker
I'm not sure what that rating is, it was mentioned in another thead
So you might end of up a 100a sub, but only being able to feed it with 60a
Move the circuits as you state

Yes, if you only need 3 circuits out in the workshop then 3 circuit runs might be easier



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Old 01-30-2010, 01:59 PM   #12
 
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Quote:
Originally Posted by Scuba_Dave View Post
You would only need a 100 panel
I haven't checked pricesd in a few years but a 100a main breaker panel used to go for about $60
Check & see what prices are
You really only need to move (4) circuits to the new 100 panel
That will allow room to put in a 100a 240v breaker to feed the 100a sub
And a 50a 240v breaker to feed a sub in the workshop

OR, just move 2 circuits & run single circuits as needed to the workshop
Myself I'd prefer a sub in the workshop if it's any distance

I'm not sure on the meter issue
If the main breaker on your panel states 100a then that is all you have in that panel
Is the garage fed from this panel ?
Any pic of the meter setup, any breakers out there ?
Scuba Dave... you are awesome for taking time to help me. I really appreciate it!

My main box with the 100a main feeds the garage sub via a tandem circuit that is 50a. In that garage sub I have runing 3 20a for lights and outlets, and a 50 amp circuit powering my 240v arc welder. that works fine.
The workshop is about 15' from my main box.
I would like to run 3 20a circuits into the work shop. Im guessing I could just run 3 12g wires to the workshop from the main circuit and not have to spend the cash on a 3rd sub and 6 guage wire. Am I right? can I feed the new sub with a tandem 50a just like my other sub in the garage?
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Old 01-30-2010, 02:06 PM   #13
 
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So Ill buy a 100a sub, move 5 15a ciruits from the main to the new sub. in those 5 spaces i created in the main I will run 1 50a to power the sub, and 3 20a running to the workshop. That is how to do it...right?
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Old 01-30-2010, 02:06 PM   #14
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Yup, 15 feet is easy to run the 3 circuits you need
Id' just run the circuits instead of another sub

NEC table 310.16 if you use #6 wire you can do a 60a sub
You need 2 black, 1 white & a #8 or #10 green ground

For 50a you would only need #8 wire & #10 ground

If you do a 60a sub I would just run the workshop off the sub
Less wires to move
Unless the sub will be further away then the main panel
All depends upon existing wire & what makes sense/is easier
My sub is about 3' away from my main
The whole area (4x8) is setup for wiring, network/phone/TV etc

I've had lots of people help me out...so I return the favor



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Old 01-30-2010, 02:08 PM   #15
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Quote:
Originally Posted by mountain_guy View Post
So Ill buy a 100a sub, move 5 15a ciruits from the main to the new sub. in those 5 spaces i created in the main I will run 1 50a to power the sub, and 3 20a running to the workshop. That is how to do it...right?
Yes exactly
I only mention the 60a instead because breakers are usually about the same in cost & wire isn't that much more for the short distance



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